Research On The Theory And Key Technology Of Digital RF Tansmitter Based On Mapping Modulation

With the development of military electronic system and mobile wireless communication,high integration and low power consumption are required for radio frequency(RF)transmitter.The traditional analog RF transmitter is facing great challenges while the digital RF transmitter is regarded as one of the important development directions of RF transmitter.However,the existing researches on digital RF transmitter have many problems,such as limited carrier frequency agility,high implementation complexity of transmitter circuit architecture,and poor transmission signal performance(evaluated by adjacent channel leakage ratio(ACLR),error vector amplitude(EVM),coding efficiency(CE)and so on).Thus,it is urgent to propose a new digital transmitter theory and circuit architecture with low implementation complexity.Therefore,this thesis presents a mapping modulation theory and systematically studies the single-band,multi-band,outphasing digital transmitter and its key technologys based on mapping modulation.The main contributions of this thesis are as follows:(1)Mapping modulation theory and the corresponding low complexity transmitter architecture are proposed.Aiming at the problem of limited carrier frequency agility,high implementation complexity and poor signal performance of digital transmitter,the mapping modulation theory is proposed firstly,which the digital up-conversion and quantization modulation is realized based on mapping table.Secondly,the theoretical analysis model and the optimization methods of key parameters are proposed to analyze the noise performance of mapping modulation to improve the signal-to-noise Ratio(SNR)and CE performance of the transmitted signal.Finally,a digital transmitter with low complexity and low power consumption is implemented based on the proposed circuit architecture.Compared with the fully parallel delta-sigma modulation(DSM)-based transmitter,the total power consumption is reduced by 75% and dynamic power consumption is reduced by 90%.(2)An optimized mapping modulation method is proposed to improve clean bandwidth(CBW)performance.Aiming at limitation of CBW performance caused by high quantization noise near carrier frequency of digital transmitter,an optimized mapping modulation method was proposed.Secondly,the concept of noise factor is introduced to analyze the noise performance,and the mapping between IF complex signal and digital RF sequence is realized by selecting the digital sequence with low noise factor in the CBW.The proposed method can greatly suppress the quantization noise near carrier frequency,and therefore improve the CBW of transmitted signal by more than 3 times.In addition,the optimized mapping modulation method is applied to the optimized carrier frequency adjustment scenario and in-band carrier aggregation scenario,realizing a more agile and simpler digital transmitter architecture,and further reducing the resource consumption of the system,among which the memory resources are reduced by up to 90%.(3)The method and implementation architecture of multi-band digital transmitter based on mapping modulation are proposed,and three optimization techniques are given.To meet the multi-standard and multi-band requirement of RF transmitter,a multi-band digital RF transmitter architecture based on mapping modulation is firstly proposed.Subsequently,the dual-band amplitude factor selection method based on noise factor is discussed to improve the ACLR performance of dual-band transmitted signals.A dual-band circuit architecture based on two-stage mapping modulation technology is proposed to reduce the mapping table size of dualband mapping modulation.The generation reason of harmonic noise in dual frequency mapping modulation is studied,and an optimized selection method of dual frequency digital sequence is proposed to suppress harmonic noise.Finally,the low-complexity multi-band(dual-band,triple-band,four-band)digital transmitter with is realized,in which the multiplication operation resources are reduced by up to 95%.(4)The method and architecture of outphasing digital transmitter based on mapping modulation are proposed.In order to further improve the transmitted signal performance of digital transmitter,combined with outphasing modulation technology,a digital outphasing transmitter based on mapping modulation is firstly proposed,and the low implementation complexity circuit architecture without real-time outphasing decomposition is presented.Secondly,a mathematical model for mathematical model for analyzing outphasing mapping modulation is proposed.The selection of amplitude factor of outphasing mapping modulation is discussed.The optimized selection method of the outphasing digital sequence combination is proposed to reduce the RF noise after combination of outphasing signals.Compared with the reported methods,the agility of frequency conversion is improved and the quality of transmitted signal is improved,in which the ACLR performance is improved by more than 5 d B.The research contents of this thesis verify that the digital transmitter based on mapping modulation has high carrier frequency agility,low implementation complexity and better signal quality,which is of great significance to promote the application of digital RF transmitter in the military integrated RF system and next generation mobile wireless communication system.